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Trying to make decisions on the way to go, in order to get some experience of 4th axis machining. The capacity of one of the 100mm Chinese harmonic drives would suffice. Or I could convert a Vertex D/head. Anyone have any experience of the Chinese units please.
Also keen to know this as Ill be looking at a 4th axis soon for my new machine.
I got a 4th axis bundled my 3040 machine. I find that mechanically it's not bad at all bad (reasonable bearings and tailstock) , but it's seriously let down by the puniest stepper I've ever seen and a tommy bar chuck that's really awkward to use insomuch as it's not very well built and runs of true by varying amounts dependant on how much you tighten it. It might be worth a look if you already have a chuck and a stepper kicking about that you can press into service and would definitely well enough for you to get the hang of using 4 axiz on very light duty objects but for me that's about their limit.
Col.
For me, id remove the stepper and put a servo on. Sorted.Quote:
Originally Posted by Seafax
Thanks for info - Col, could you advise size of the stepper, spec. or dimensions. Also do you have the 100mm chuck.
I have the 75mm chuck with a nema 23 1.8NM 3 amp stepper.
Can you link one of these harmonic drives please?Quote:
Originally Posted by Leadhead
Hi - ebay search for CNC harmonic 4th axis.
Link: https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2060353.m570.l1313.TR0.T RC0.H0.XCNC+harmonic
Great, thanks.
When can we expect your review?:smug:
Me? Nothing yet, need to finish Thor first.Quote:
Originally Posted by Leadhead
Hi! Did you ended up using hte 4th axis harmonic drive? I just got one and wired up. It looks ok but i notice the chuck has this huge play. Do you also have it? I thought it should be gapless with not backlash. I am confused. :-)Quote:
Originally Posted by Chaz
Here the video showing it.
https://www.youtube.com/watch?v=uSB-UlZzBjQ
Thanks for the help!
Hi, nope - didnt look at it.Quote:
Originally Posted by Rey8801
Ah ok. Well if you will have justa minute maybe try to replicate what I have shown in the video. In my drive the front can move without turning the stepper motor. I thought harmonic should be backlash free or gapless as the seller mentioned in the product title. Thanks! :-)
Harmonic drives have very low backlash, that looks like something loose inside where it is attached to the gear, bad key-way, loose bolts ??
Not sure how it is connected inside but it is strange to me too. I might try to open it up in front. The runout is not measurable so will be really a pity if that can no be solved.Quote:
Originally Posted by johnsattuk
Report here as well.Quote:
Originally Posted by johnsattuk
I made a video yesterday during the disassemble, just a random talk late at night, but it's useful to actually show how it is made. The backlash it's really from what I would call harmonic drive, but I am not an expert. What surprise me is that there are other users from this forum with the same drive and they claim almost ZERO backlash, so can be that I got a faulty one with maybe components out of tollerance. It seems the mesh inside the gearbox has a play before lock in place.
https://youtu.be/qgmcX7lL5zw